In 'Tully,' Charlize Theron And Mackenzie Davis Make A Great (Au) Pair

When it comes to undercutting her glam loveliness for the sake of a meaty role, Charlize Theron is the champ of champs. Meaty's the word: Having packed on the pounds and several tons of vicious attitude to play serial killer Aileen Wuornos in 2003's Monster and shed a (virtual) limb or two for 2015's Mad Max: Fury Road, Theron comes to us in Jason Reitman's Tully lugging a baby bump so massive, you can barely see her bringing up the fleshy rear.

Lest we doubt her commitment to looking like most women do shortly after giving birth, there's a candid tracking shot from behind of her character — third-time mom Marlo — trying to outrun a lissome young athlete in the park. Like the rest of this maddeningly uneven movie, the scene is a little bit funny, a bigger bit cruel, and with it all, oddly moving.

Luckily, with Theron it's never just about the prosthetics or the visual gags. For her Marlo, it's all in the eyes, bleary with fatigue and the stress that comes with being the mother of two small children (one of them with special needs, though Marlo's too exhausted to see anything but the special) and trying to cope with the third, who seems never to stop crying.

On schedule, up pops the obligatory set piece where Marlo throws a fit in a school principal's office. Yet Theron plays even this scenario with the slow deliberation of a woman quietly nearing the end of her rope. Marlo's steady but preoccupied husband (Ron Livingston) isn't much help, and though at first she resists when her smug, well-heeled brother (Mark Duplass) presents her with a night nanny, she succumbs when the baby's arrival finally grinds her to a spaced-out standstill.

Enter Tully (a very good Mackenzie Davis), a slightly manic yet unflappable pixie girl who also happens to be the fulfillment of every overwhelmed parent's compensatory dreams. Without turning a hair Tully cooks, cleans, gets baby to breastfeed, bakes fluorescent cupcakes for the kids' entire class. Over time she also becomes Marlo's confidante; the two become besties; the new mother blooms; the household grows a sly touch of eros. Until, suddenly, there comes a mischievous twist that steers this most realist of dramedies clear into fresh genre waters. And if, like me, you didn't see the denouement coming, you may say to yourself why, of course.

Tully is written by Diablo Cody, who also wrote the screenplays for Reitman's smash hit Juno and for his bracing Young Adult, in which Theron starred as a pushing-forty narcissist belatedly trying to get her love-life on track. Cody and Reitman make a marketable team, smoothly packaging topicality in a skin of buoyant mischief that manages to straddle the glib and the true. At her most complacent, Cody can be a master of the breezy put-down, and here she gets off a few volleys of cheap shots at the expense of bougie-hipster parents — not like us, no, never — who worry about trace elements of caffeine in their decaf, and whose nannies have graduate degrees in early childhood development.

Does it matter that Cody, who wrote Tully after hiring a night nanny to look after her third baby, and Theron, who has two adopted children of her own, can both afford all the help they need? In the sense that Marlo, who both wants and needs to get back to her job in human resources, is portrayed as a 99-percenter with 1-percenter problems, it's likely that for most moviegoers, Tully will end up as a wishful fantasy on more levels than one.

What saves the movie from unbearable smugness is the lovely duet of Theron and Davis playing their deepening partnership without either posturing or a disclaiming wink at the audience. So much so that we can believe in Tully, a mere stripling with troubles of her own, serenely guiding a woman many years her senior through the black comedy and the sludge of early motherhood, through her dreams of regressive escape, and on into the grownup zone.

If Juno was about the ramifications of getting pregnant way too young, Tully worries that middle age isn't much of a help when you're trying to juggle multiple tasks and roles within a raging-hormonal body you barely recognize. If Young Adult insisted that an overgrown child stuck in eternal arrested development doesn't deserve an upbeat ending, Tully serenely suggests that fulfillment is about the repetition of dreary routine made bearable by the love of others, and the love you bear for them. Tully may be rounding out a trilogy, but I suspect that Reitman and Cody are re-upping as we speak for What to Expect When You're Re-Feathering the Empty Nest.